1. Field of the Invention
This invention relates to preventing moisture precipitation at sensitive machine parts and to measuring the moisture to determine leaks within the housing of an electric machine, the winding of which is cooled by water and in which a gas stream, cooled by a heat exchanger, is circulated within the housing.
2. Description of the Prior Art
In electric machines which are water-cooled at least in the stator, a hydrogen cooling gas flow is generally maintained within the hermetically sealed housing for cooling the stack of stator laminations. This cooling gas stream is cooled by coolers which are arranged at the ends of the machine and through which cooling water flows.
However, a certain amount of residual moisture is always contained in the hydrogen gas. The dew point therefor is normally determined by the water entrance temperature of the hydrogen coolers. When a cooler is disconnected in operation, the temperature of the gas can fall below its dew point under unfavorable conditions, and water can precipitate at sensitive parts of the machine. In addition, such changes often result in a residual moisture of variable magnitude, depending on whether it is precipitated at the coolers or on other parts or whether it is present in the gaseous state. A variable moisture impedes a correct moisture measurement within the housing, and determination of leaks in the water-cooled windings by measurement of the moisture content is ineffective and at best uncertain.